“I can’t believe I’m on probation. Papa will kill me,” said Agatha, possibly not exaggerating. One never knew with parents who sent their daughters to Mademoiselle Geraldine’s.

Sophronia tried out tactics in her head. Just now, she had nothing to say that wouldn’t sound falsely modest. Even if she told them her suspicion that she was being set up, she’d sound defensive. She would have to hope that Agatha and Sidheag would figure it out on their own. She felt certain, however, that she could count on Dimity.

Sophronia cocked her head to one side to look at her best friend.

Dimity looked away and said something sympathetic to Agatha.

Sophronia bit her lip and stared at her hands. She had thought Dimity would stay loyal, just a little bit.

The girls continued to ignore her all that day. It made for lonely classes and an uncomfortable evening meal. Sophronia tried not to let it affect her. They should recover from their resentment if she did nothing to aggravate them. But every time she performed a task well or answered a question correctly during lessons, she could feel the dislike. Several days saw no change to this pattern, and even Dimity still wasn’t talking to her, which was particularly awkward, as they shared a bedroom. Sophronia was both annoyed and hurt. She stopped having an appetite at dinner and started filching the occasional roll for later. She even contemplated not following Dimity when the girl crept out of quarters for her assignation with Lord Dingleproops. But since Sophronia figured that the letter was some kind of cruel joke and that the boy wouldn’t show up, she simply couldn’t let her friend walk into heartbreak alone. So when Dimity sneaked out of quarters, having changed at bedtime into her best evening dress rather than a nightgown, Sophronia followed.

Dimity used a series of evasion and climbing techniques to get around the ship. She held perfectly still and flattened herself against walls so mechanicals patrolling the hallways slid right by. It made getting around after hours very slow, and there was always a risk of discovery whenever a maid rolled into sight. Dimity was better at it than Sophronia had thought, which made her proud. After all, Sophronia had taught Dimity everything she knew on the subject.

Sophronia stayed out of sight, tracking her friend effortlessly, knowing Dimity was headed to the back squeak deck. Sophronia had it easier. She used a small grappling rope knotted at stages for climbing, her own personal invention. It was undemanding to creep along the same level, but up and down could be a challenge on an airship hull. Sophronia had scavenged rope from the sooties and asked Vieve to build her a hook and the emission hurlie. The hurlie was a kind of turtle-shaped device that clipped to Sophronia’s wrist. Vieve was fond of things that clipped to wrists. Once Sophronia flipped the catch at the turtle’s tail, a spring-loaded release mechanism allowed her to fling the turtle’s shell, with the grapple underneath, and the rope followed behind. Best of all, Sophronia didn’t have to use the ladder from Lady Linette’s balcony every time she wanted to visit the sooties.

Instead of climbing up onto the deck after Dimity, Sophronia continued edging around to the very back of the ship. She reeled in her grappling hook and hung off the side, looking into the skies, hunting for an airdinghy. Above her, the squeak deck was abandoned under its great balloon, except for Dimity. Dimity’s view was obstructed by the smokestacks, mast, and propeller, but Sophronia could see around and between them. The school floated with the breeze, so the air around them felt still and windless.

Hours seemed to pass, and Sophronia was convinced that the letter was a hoax. Then she saw it, coming up from below—an airdinghy. There was someone crewing it, but she could make out nothing from her vantage point but its sail and four balloons.

Above, Dimity’s silhouette came to the rails and looked out, but she could not see what Sophronia saw.

Sophronia wondered how Lord Dingleproops intended to board without setting off any of the school’s alarms. The back was the safest choice, since teachers and staff slept in the forward section and students in the middle, but there were mechanicals everywhere. Several had protocols that had them do nothing but look for shapes in the sky and set off alarms in teachers’ bedrooms when they saw something.

Fearlessly, the airdinghy rose up until it was almost level with Sophronia. She heard Dimity give a glad little cry of welcome. When Sophronia could finally see into the gondola, there were two men, not the one boy Dimity expected. Sophronia had met Lord Dingleproops once at a party; he was a reedy, chinless, redheaded blighter, and while tall and strapping, he was not bulky. Both of these men were bulky. There was certainly something wrong.

As the airdinghy rose higher, Sophronia squinted, trying to make out more of the figures in the dark. Then she realized what was off about them. No top hats. No gentleman would ever meet a lady without appropriate headgear, even if that meeting was a joke. Whoever these men were, they were not noblemen. Plus Lord Dingleproops was a member of the Pistons, a social club. A Piston’s top hat was his marker, his sign of status; to travel without it was unthinkable.